Grinding machine with wheel dresser



1943- J. w. RUNDT GRINDING MACHINE WITH WHEEL DRESSER '7 Sheets-Sheet 1 Filed Feb. 19, 1945 Aug. 17, 1948. w RUNDT 2,447,478

GRINDING MACHINE wmx WHEEL nmassaa Filed Feb. 19, 1945 '7 Sheets-Sheet 2 //o36 as Aug. 17, 1948. J w, RUNDT GRINDING nmcums WITH WHEEL DRESSER '7 Sheets-Sheet 3 Filed Feb. 19, 1945 w l A@ Aug. 17, 1948. J w RUNDT 2,447,478

GRINDING MACHINE WITH WHEEL DRESSER Filed Feb. 19, 1945 7 Sheets-Sheet 4 lN/En/rofi l "p til mm I 17 15 fir roRME/S.

Au 17, 1948. RUNDT 2,447,478

GRINDING MACHINE WITH WHEEL DRESSER Filed Feb. 19, 1945 7 Sheets-Sheet 5 IE M J. W. RUNDT GRINDING MACHINE WITH WHEEL DRESSER Aug. 17, 1948.

7 Sheets-Sheet 6 Filed Feb. 19, 1945 llvl/EMToP:

M6 HTTQRA/EK Patented Aug. 17, 1948 UNITED STATES PATENT OFFICE GRINDING MACHINE WITH WHEEL DRESSER John W. Rundt, Canton, Ohio, assignor to The Timken Roller Bearing Company, Canton,

Ohio, a corporation of Ohio Application February 19, 1945, Serial No. 578,626

This invention relates to improvements in grinding machines in which means are provided for dressing and truing the working face of the grinding wheel without removing said wheel from said machine. The objects of my improvement are to provide a wheel dressing means which is entirely automatic in operation so as to relieve the operator of the grinding. machine of all responsibility of dressing the grinding wheel thereof; that will perform the dressing operation while a ground work piece is being replaced with a work piece that is to be ground; that will 22 Claims. (Cl. 51-2) housing and the air and oil cylinders and oil resprovide for dressing the grinding wheel after a predetermined number of work pieces have been ground; that is readily adjustable to dress the grinding wheel after any given number of work pieces have been ground; that will produce a working face on the grinding wheel that is more smooth and accurate than is possible by hand methods; that can be adapted for dressing grinding wheels having working faces of straight or irregular profile; that will accurately control the amount of material removed from the wheel during each dressing; and that will have other advantages hereinafter appearing. The invention consists in the automatic wheel dressing and truing mechanism and in the parts and combinations and arrangements of parts hereinafter described and claimed.

In the accompanying drawings, which form part of this specification and wherein like symbols refer to like parts wherever they occur.

Fig. 1 is a front end elevational view of a grinding machine provided with a grinding wheel dressing and truing mechanism embodying my invention, 7

Fig. 2 is a fragmentary view showing the wheel dressing and truing unit in side elevation and the grinding wheel in end elevation,

Fig. 3 is a fragmentary view of the parts shown in Fig. 2, looking in the direction of the arrows 33 in Fig. 2, l

Fig. 4 is a vertical sectional view on the 'line ervoir in vertical section,

Fig. 13 is a fragmentary vertical section on the 3 line l3-I3 in Fig. 11,

Fig. 14 is a horizontal section on the line I l-44 in Fig. 11,

Fig. 15 is a fragmentary side elevational view of the portion of the housing containing the mechanism for causing the wheel dressing unit to operate after a predetermined number of work pieces have been ground,

Fig. 16 is a horizontal section on the line l6| 6 in Fig. 15.

Fig. 17 is a vertical section on the line l'I-ll in Fig. 15,

Figs. 18, 19 and 20 are horizontal sectional views on the lines lB-I'B', l9 --l9 and 20-20, respectively, in Fig. 17 and 21,

Fig. 21 is a vertical sectional view on the line ii-2| in Fig. 18,

Fig. 22 is an end elevational view of theratchet operated cam wheel for controlling'the master valve of the fluid control system fortheidressing and truing unit,

. Fig. 23 is a vertical section on in Fig. 11,

Fig. 24 is a diagrammatic view, showing the grooved working face of the grinding wheel and the cam plate for determining the contour of said Working face; and

Fig. 25 is a diagram similar to Fig. 24, showthe tu 23-23 ing a grinding wheel with a beveled working face and a cam plate and rocker arrangement for moving the diamond clear of said face during the return movement of the traversing slide.

In the accompanying drawings, my invention is shown embodied in a grinding machine comprising an abrasive grinding wheel I fixed to a belt driven spindle 2 journaled forrotary and angular movement in a pedestal bearing 3 provided therefor on a wheel slide 4 mounted for horizontal movement on a suitable slideway 5 provided therefor, on the top of the table or stationary main body portion 6 of said machine. The spindle '2 is disposed crosswise of the wheel slide I which, in accordance with common practice, is reoiprocated on the slideway 5 by a suitable manually operated fast acting lever mechanism (not shown) to move the grinding wheel I into and out of engagement with the rotating work piece (not shown) that is to be ground. This lever mechanism is adjusted to set the feed position of the wheel slide 4 by means of a hand wheel I fixed to screw 8 that is carried by said wheel slide and operatively engages said lever mechanism. The construction of grinding machine thus far described is well known and it is considered unnecessary to illustrate it in detail.

The mechanism for truing and dressing the grinding wheel I is supported on a raised plate 9 that is formed integral with the wheel slide 4 and inclines downwardly toward the grinding wheel 35 journaled on a bolt 36 fixed to the swivel spindle 2 on one side thereof. Said mechanism comprises a feed-up slide III mounted on the inclined plate 9 for movement toward and from the grinding wheel spindle 2, a traversing slide II mounted on said feed-up slide for movement lengthwise of said spindle, and a diamond slide I2 mounted on said traversing slide for movement towards'and away from the grinding wheel I. The sliding connection between the feed-up slide I0 and the inclined supporting plate 9 comprises a dovetailguide plate I3 that is fixed to the top of said plate and fits in a dovetail groove I4 in the underside of said feed-up slide. The sliding connection between the traversing slide II and the feed-up slide I0 comprises a plate I5 that is secured by a pivot I6 to said feed-up slide for swiveling movement thereon and has a dovetail guide rib I! that fits in a dovetail groove I8 in the bottom of said traversing slide. The swivelmounted guide plate I5 for the traversing slide II is secured to the feed-up slide ID in the desired position of adjustment by means of a cap screw I9 that extends through an arcuateslot in said plate and is threaded in said feedup slide. The sliding connection between the diamond slide I2 and the traversing slide II comprises a dovetail guide rib 2I that is integral with the top of said traversing slide and fits in a dovetail groove in the underside thereof. The lower or grinding wheel opposing end of the diamond slide I2 has a bore 22 therein adapted to receive and support a telescopic or extensible diamond holder 23 which is locked in said bore by means of set screws 24. The diamond holder 23 terminates at its exposed outer end in a tapered portion having a diamond 25 set therein for truing and dressing the peripheral working face of the grinding wheel I.

The traversing slide II is operated in one direction of its sliding movement by means of a hydraulic cylinder 26 which is fixed to one end of said slide and has a piston 21 disposed in end- 'wise abutting relation to the corresponding end of the guide rib I! for said slide. The traversing slide II is moved in the opposite direction of its sliding movement by means of a coil compression spring 28 which is mounted in a longitudinal roove -I'Ia in the guide rib I! for said slide with one end in abutting relation to one end of said I During the reciprocating movement of the traversing slide II, the diamond slide I2 carried mounted guide plate I5 for the traversing slide II. As shown in the drawings, the roller supporting bolt 36 is disposed in a slot 3! that is located in the swivel mounted traversing slide supporting plate I5 and is disposed parallel to the guide rib I'I thereon. The roller supporting stud or bolt 36 is adjustable longitudinally of the elongated slot 31 by means of an adjusting screw 38 that is journaled for rotary but nonaxial movement in the swivel plate I5 and is threaded t rough said bolt and is provided with a knurled operating knob 39. The cam plate 32 is yieldably held in engagement with the roller 35 by means of a coil spring 40 mounted around a screw 4I that is fixed to the traversing slide II and projects from one side thereof. The screw 4I extends through a tubular housing 42 fixed to the adjacent end of the diamond slide I2; and the spring 40 is located in said housing with one end seated against the inner end thereof and with the other end seated against the head of said screw. By this arrangement, the spring 40 forces the diamond slide I2 in the direction of the grinding wheel I and holds the cam surface 34 of the cam plate 32 fixed tosaid slide in engagement with the roller 35 journaled on the swivel mounted guide plate I5 for the traversing slide II, whereby the wheel dressing diamond 25 travels back and forth across the peripheral work grinding face of t e grinding wheel during the reciprocating movement of the traversing slide II along a path corresponding to the contour of the cam edge 34 of the cam plate 32.

The feed-up slide I0 is moved along the guide plate I3 in the direction of the grinding wheel I to remove a certain amount of stool: from the working face thereof during each dressing or truing operation. This intermittent feed movement is imparted to the feed-up slide I0 preferably by means of a feed screw 43 that is mounted for rotary but non-axial sliding movement in one end of said slide and is threaded into the corresponding end of the guide plate I3 therefor. The feed screw 43 is automatically rotated after each wheel dressing operation by means of a ratchet wheel 44 that is fixed to said feed screw. The feed screw 43 may also be manually rotated by a crank 45 fixed to th outer end thereof. The ratchet wheel 44 is operated by a pawl 46 which is pivotally mounted on one end of a lever 41 fixed to a horizontal shaft 48 journaled in bearings 49 provided therefor in the feed-up slide ID. The pawl 46 is yieldably held in engagement with the teeth of the ratchet wheel 44 by means of a coil expansion spring 59 interposed between said pawl and the supporting lever 41 therefor; and the feed movement of said pawl is regulated by means of an adjustable stop pin 5I which is threaded into said lever with its inner end located in a slot 52 therein in abutting relation to a pin 53 that is fixed to the adjacent end of the feed-up slide I0 ment to the ratchet wheel 44 at the end of the spring actuated stroke of the traversing slide ll preferably by means of a screw 54 that is threaded through a bracket 55 fixed to the side of said slide. The screw 54 is disposed on one side of the shaft 48 in endwise abutting relation to a dog 56 fixed thereto. whereby said screw is adapted, during the spring actuated stroke of the traversing slide l l, to rotate said dog and shaft in a direction that will impart a feed movement to the pawl 46 which rotates the ratchet wheel 44 and feed screw 43 and to thereby advance the diamond slide l2 towards the grinding wheel I. During the reverse or fluid pressure actuated stroke of the traversing slide II, the pawl 46 is drawn back and set for its next feed movement by means of a coil torsion spring 51 which is mounted on the shaft 48 with one end anchored thereto and with the other end anchored to said traversing slide. As stated above the feed movement of the feed-up slide l may be regulated by adjusting the screw 5 I. As shown in the drawings, the bracket 55, which carries the screw 54 for operating the dog 56 on the pawl operating shaft 48 is secured to the traversing slide II by means of a cap screw 56 that extends through said bracket and is threaded into a T- block 60 that is slidable in a longitudinal T-groove 6| in the adjacent side face of said slide. The stop screw receiving portion of the bracket 55 is split and provided with a clamp screw 62 for locking the stop screw 54 in the desired position of adjustment. By this arrangement, the screw 54 maybe adjusted relative to its supporting bracket 55 and said bracket may be adjusted relative to the traversing slide l I. As shown in the drawings. the dog 56 fixed to the pawl operating shaft 48 is swung by the screw-54 into engagement with the feed-up slide l0 and thus constitutes a stop for limiting the spring actuated stroke of the traversing slide H and the feed movement of the pawl 46.

The mechanism for controlling the operation of the above described wheel dressing mechanism is mounted on the body 6 of the grinding machine below and at one side of the wheel head slide 4 which is manually operated to move the grinding wheel I and dressing mechanism therefor towards and away from the work piece that is to be ground. This operating mechanism comprises a suitable normally closed bleeder valve 63 located in a conduit 64 that leads from a suitable source of cornpressedair supply to the bottom of an upright ratchet operating cylinder 65 that is secured at its upper end to a suitable supporting housing 66 fixed to the side face of the body 6 of the grinding machine. The mechanism for opening the normally closed valve 63 to permit flow of air through the supply pipe 64 to the ratchet cylinder comprises a cam plate 61 suspended by means of a pair of parallel links 68 from a supporting plate 69 that is movable with the wheel slide 4 and is adjustable longitudinally thereof. The link supporting plate 69 is slidably supported on a longitudinal guide block 4a fixed to the side face of the wheel head slide 4; and the longitudinal sliding connection between said supporting plate and guide block comprises a rib 10 on the inner side face of said guide block that is slidable in a longitudinal groove 1| provided therefor in the outer side face of said guide block. The groove 1i has an undercut or widened bottom portion adapted to receive the heads of T-bolts 12 having nuts 13 threaded on the outer ends thereof for clamping the plate 69 to the guide block 4a in the desired position of adjustment.

Mounted for vertical swinging movement on the housing 66 is a lever 14 which overhangs the normally closed valve 63 and has a depending stud 15 that is supported on a roller 16 on the exposed upper end of the stem 11 of said valve. This valve stem 11 moves downwardly to open the valve 63 and, normally supports the lever 14 without being depressed thereby. The lever 14 has a roller 18 journaled on the free end thereof in position to be engaged by the collapsible link supported cam plate 61 and force the valve stem 11 downwardly to open the valve 63 when the wheel slide 4 is moved outwardly to move the grinding wheel I away from the work piece. The cam plate 61 is normally held down in position for engagement with the roller"18 on the valve opening lever 14 by means of a latch arm 19 which is pivoted, as at 80, to the adjacent side of the supporting plate 69 for vertical swinging movement relative thereto and has a hooked end portion 8i that interlocks with a corresponding hook 82 formed integral with the rearmost cam plate supporting link 68 and thus prevents upward movement of the cam plate 61. The hooked end 8| of the latch 19 is yieldably held in locking engagement'with the hook 82 on the rearmost cam plate supporting link 68 by means of a coil spring 89 interposed between the top of said latch arm and the underside of a lug that extends rearwardly from said link in overhanging relation to said latch arm. Vertical swinging movement of the latch arm 19 is limited by means of a screw 9| which extends through a vertical slot 9la therein and is threaded into the adjacent side of the cam plate link supporting plate 69 fixed to the wheel head-slide 4. The supporting plate 69 is moved longitudinal-1y of the wheel slide 4 to adjust the cam plate 61 relative to the roller 18 on the valve actuating arm 14 preferably by'means of a hand wheel 84 fixed to a feed screw 85 which extends longitudinally of said wheel slide with its inner end threaded through a lug 86 on said supporting plate and its outer end journaled in a plate 81 fixed to the outer end of said wheel slide.

The upright ratchet operating cylinder 65 contains a piston 92 which is forced upwardly in said cylinder by means of the air supplied to the bottom thereof through the supply pipe 64. The piston 92 is moved downwardly in the cylinder 65 by means of a coil spring 93 that is supported in an axial bore 92a provided therefor in the upper end of said piston with one end seated in the bottom of said bore and with the other end seated against the underside of the head portion 94a of a pin or plunger 94 that extends downwardly into said spring and forms a guide therefor. The head 94a has a conical top portion 94b that is held by the upward thrust of the spring 93 in a downwardly opening conical recess or seat 95 provided therefor in the housing 66. The piston 92 has a radial arm 96 rigid therewith at the upper end thereof that has a bifurcated end portion that straddles a vertical adjusting screw 91 that is journaled in the housing 66 alongside of said piston for rotary but non-axial movem nt. and has a knurled operating knob 91a at its upper end. The adjusting screw 91 has a stop allll orv lug 98 threaded thereon intermediate the ends thereof that is notched to straddle the piston 92. The stop ing 98 is located below the radial arm 96 on the upper end of the piston 92 and thus serves as a stop for said arm to limit the downward travel of said piston. The engagement of the radialarm 96 of the piston with the screw 91 prevents rotation of said piston; and the engagement of the stop lug 98 with said piston prevents rotation of said stop lug. By this arrangement, the rotation of the screw 91 causes the stop 93 thereon to travel lengthwise thereof relative to the piston 92 and thus lengthen or shorten the downward stroke thereof.

Joumaled on a horizontal stub shaft 99 fixed to the housing 06 is a ratchet wheel I which is actuated by means of a pawl I0l pivotally supported on the outer end of a supporting arm I02 which is also journaled on said shaft. The pawl Ill is pivotally supported on a horizontal stud I03 fixed to the arm I02 with its end siidably supported in a slideway I04 provided therefor in the adjacent side face of the piston 92, whereby said pawlsupporting arm is oscillated on its supporting shaft 99 by the reciprocating movement of the piston 92 to impart a feed movement to the pawl IOI during the upward movement of the piston and a return movement of said pawl during the downward movement of said piston. The pawl III is held in engagement with the teeth of the ratchet wheel I00 by means of a spring I having one end anchored to said pawl and the other end anchored to the supporting arm I02 therefor. When the piston 92 moves downwardly, the pawl IOI rides over the ratchet teeth without imparting any movement to the ratchet wheel I00. During this return movement of the pawl III, the ratchet wheel I00 is prevented from moving therewith by means of a second pawl I" that is pivotally secured to the housing 66 and'is held in continuous contact with the ratchet teeth by means of a coil spring I01 having one end fixed to said pawl and the other end fixed to said housing.

Keyed to an extended hub portion I000; of the ratchet wheel for rotation therewith on the stub shaft 90 is a rotary wheel I08 having two axially spaced edge cams I09, H0 thereon, the edge cam I09 having a single arcuate notch I09a therein and the other edge cam having four similarly shaped equally spaced notches 0a therein. Friction disks I I I are clamped to remote end faces of the ratchet wheel I00 and pawl supporting arm I02 by means of a nut II2 threaded on the outer end of the stub shaft 99. These disks operate as friction brakes to prevent overrunning of the cam and ratchet wheels. The cam wheel is reversible end for end so as to bring either edge cam thereof in position for engagement by a roller II3 joumaled on'a supporting lever II 4 that is pivotally secured to the housing 65 for vertical swinging movement towards and away from said cam wheel.

The free end of the roller supporting lever H4 is held in engagement with the edge of the cam I09 in line therewith by a vertically disposed master slide or plunger valve H5 for the ratchet operating cylinder 05. The master slide valve H5 is slidable in a vertical valve bore IIO provided therefor in the ratchet operating cylinder 55 and a spring IISa located in the bottom of said bore forces said valve upwardly against the lever H4 and holds the roller I I3 thereon against the edge cam I09. When the roller II3 on the lever H4 is in contact with the un-notched portion of the edge cam I09, the slide valve H5 is forced downwardly in the valve bore I I6; and'when said roller seats in the notch M91: in said cam, said valve is forced upwardly in said bore by the spring I I5a.

The master slide or plunger valve II5 has two annular grooves H1, H8 therein that are spaced apart longitudinally thereof. The ratchet operating cylinder 05 has a radial passageway II9 therein that passes through the valve bore H6 and opens into the upper portion of the pressure space or chamber I20 in said cylinder below the piston 92 therein. The passageway II9 has a branch passageway I2I which opens into the lower portion of the chamber I 20 and is provided with an inwardly opening ball check valve I22 which permits flow of air through the branch passageway to the chamber but not from the chamber through the branch passageway. The passageway I I9 communicates through a pipe or conduit I23 with an air cylinder I24 hereinafter referred to. The slide valve supporting bore II6 also has diametrically opposed radial ports I25, I26 in communication therewith above the passageway H9, the port I25 communicating with the air cylinder I24 through a pipe or conduit I21 and the port I20 communicating with a manually operable valve I20 through a pipe or conduit I29. When the plunger valve I I5 is raised, the annular groove II1 therein opens the passageway H9 and establishes communication between the cylinder and the air cylinder I24 through the conduit I23 and said valve covers the ports I25 and I20 and cuts all communication between the air cylinder I24 and the valve I20 through the conduits I21 and I29. In the depressed position of the master slide valve 5, the passageway H9 is closed to cut off communication between the cylinder 65 and the air cylinder I24 through the pipe I23, and the ports I25 and I26 are opened by the annular groove I I8 in said valve to establish communication between said air cylinder I24 and said valve through the pipe I29.

The air cylinder I24 is mounted vertically in the housing 60, a master hydraulic or oil cylinder I30 is mounted in said housing above and in vertical alinement with said air cylinder, and a piston I3I that is common to both cylinders has its lower'end working in the air cylinder and its upper end working in the master cylinder. The piston is forced downwardly in the cylinders I24 and I 30 by a spring I32 in the upper cylinder I30 and is forced upwardly in said cylinders by the air pressure supplied to the lower cylinder I24 by the conduit I23 leading from the pressure chamber I20 of the ratchet operating cylinder 05 or by the conduit I21 which, in the depressed position of the master valve II5, is placed in communication with the conduit I29 leading from the manually operable bleeder valve I29. The piston I3I has a radial arm I33 that is rigidly secured thereto between the cylinders I24 and I30 and is adapted to seat-on the upper end of the lower cylinder I24 and limit the downward stroke of said piston. The arm I 33 has a vertically disposed trip rod I34 threaded therethrough for axial adjustment relative thereto. The reciprocable trip rod 634 extends upwardly through a slide bearing I35 provided therefor in the top of the housing 66 and is adapted, when the piston I3I is forced upwardly and the latch bar 19 is located above said rod, to swing the latch bar upwardly and lift the hook 8| thereof out of engagement with the hook 82 on the link supported cam plate 61. As shown in the drawings, the air supply pipe 64 is provided in advance of the cam operated valve 63 with a branch 04a which is adapted to communicate with the conduit I29 through the manually operable valve I20. The pipe 64 is also provided in advance of the cam operated valve 63 with a conventional air line iubricator and pressure reducing valve I36 and a gage I31.

The pressure chamber l30a of the oil cylinder I30 communicates through a series of radial ports I38 with an annular chamber I39 formed in said cylinder; and a passageway I40 leads from said annular chamber to an oil reservoir I M formed in the housing 66. The passageway I40 has a ball check spill valve I42 therein which permits flow of oil from the annular chamber I39 to the passageway I40 while preventing flow of oil from the reservoir I39. to said annular chamber; and said passageway has an upwardly extending branch passageway I43 that opens through a radial port I44 into the pressure chamber I30a. As shown in the drawings, the branch passageway I43 is provided with a ball check refill valve I45 which permits flow of oil from the reservoir I4I to the pressure chamber I38a, while preventing a return flow of oil from said pressure chamber to said reservoir. The radial port I44 leading from the pressure chamber I30a of the oil cylinder I30 communicates with the traversing slide operating cylinder 26 through the flexible pipe or conduit 30.

In operation, each time the operator manipulates the hand'wheel I to move the wheel slide 4 and the grinding wheel truing and dressing mechanism thereon away from the finished workpiece to facilitate removal thereof from the grinding machine,- the collapsing cam 61 carried by said wheel slide rides over the roller I8 journaled on the free end of the pivotal valve operating arm I4 and swings said arm downwardly. This downward movement of the arm I4 opens the self-closing valve 63 in the air supplyline 64, thus admitting air under pressure to the air cylinder 65 and raising the piston 92' therein. This up-.

ward movement of the piston 92 operates the pawl I0! and imparts a feed movement to the ratchet wheel I00 and a corresponding feed movement to the cam wheel I08. Each time the wheel slide 4 is operated to replace a ground work piece with a work piece that is to be ground, the piston 92 moves upwardly in the cylinder 65 and imparts working face of said grinding wheel to the contour desired for said face.

As the piston I3I moves-upwardly in the air cylinder I24 and oil cylinder I30, the trip rod I34 also moves upwardl with said piston and presses upwardly against the underside of the latch arm I9, which moves over said trip rod when the wheel slide 4 is retracted, thereby swinging said latch arm upwardly and disengaging the hook 8| thereof from the hook 82 of the collapsing cam 61 and thus releasing said cam and permitting the valve 63 opened thereby to close. The closing of the valve 53 cuts off the air pressure through the conduit 64 to the air cylinder and opens said conduit to the atmosphere through the bleeder orifice of said valve. The length of the fluid pressure actuated stroke of the traversing slide II may be varied by adjusting the trip rod I34 axially in its supporting arm I33. Upon release of the air pressure in the air cylinder 65. the piston 92 therein is forced downwardly by the spring 93 and thus imparts a return movement to the pawl IOI relative tothe ratchet wheel I00, the safety pawl I06 preventing a return movement of said ratchet wheel during such return movement of the pawl IN.

a rotary feed movement to the ratchet wheel I00 and cam wheel I08.

When the cam wheel reaches a position where the notch I09a therein is in position to receive the roller II3 on the lever II4, the master slide valve H5 is forced upwardly by the spring 511 and opens the passageway I I9 in the cylinder 65, thereby permitting the air to flow from the pressure space or chamber I20 of said cylinder to the air cylinder I24 through the pipe or conduit I23.

The air supplied to the air cylinder I24 forces the piston I3I upwardly therein and in the oil cylinder I30. This upward movement of the piston I3I in the oil cylinder I30 forces the oil trapped in the pressure space I30a thereof through the port I44 and the flexible conduit 30 into the hydraulic cyl- I inder 26 fixed to the traversing slide I I, thus moving said traversing slide I I relative to the feed-up slide I0 against the pressure of the coil spring 28. This movement of the traversing slide II causes the cam plate 32 carried by the diamond slide l2 tO'lliOVe relative to the cam roller 35 journaled on the swivel mounted guide plate I5,

thereby causing said diamond slide to move cross- A return stroke is then imparted to the traversing slide II by the spring 28, thus forcing the oil in the cylinder 26 carried by said slide back through the flexible conduit 30 into the oil cylinder I30 and permitting the spring. I 32 to. force the piston I 3i downwardly in said oil cylinder and in the air cylinder I24. This downward movement of the piston I3I forces the air in the air cylinder I24 through the conduit I23, passageways H9 and IZI and check valve I22 into the pressure chamber I20 of the air cylinder 65, thence through the conduits 64 to the bleeder valve 63 and thence to the atmosphere. This completes the wheel dressing cycle; and the dressing mechanism remains inoperative until the step-by-step feed movement imparted to the cam wheel I08 by movement of the wheel slide to remove and replace the work pieces again brings the notch I09a in said wheel in position to receive the roller II3 on the hold-down lever H4 and permit the master valve I I5 to shift to a position which will cause the wheel dressing mechanism to again operate. The wheel dressing mechanism may be operated at the will of the operator regardlessof the position of the cam wheel I08 by manually operating the valve I28 to establish communication between the branch 04a of the air supply pipe 64 and the conduit I29, thereby permitting air to flow through the conduit I23, depressed master valve II5, and'conduit I2! to the lower end of the air cylinder I24 thus raising the piston I3| and forcing the oil from the oil cylinder I30 into the cylinder 20 fixed to the traversing slide I I.

By rotating the adjusting screw 91, the piston step 98 may be raisedor lowered thereon to lengthen or shorten the stroke of the ratchet operating piston 92 in the air cylinder and thus vary the feed movement imparted to the ratchet wheel I00 and cam wheel I08 by the pawl IOI 0perated by said piston so as to cause the dressing mechanism to operate after a predetermined number of work pieces have been ground. For instance, with a sixty-tooth ratchet wheel and the single-groove edge cam I09 and a one-tooth advance of said ratchet wheel and cam with each complete reciprocation of the piston 92, the dressing mechanismwill operate to dress the grinding wheel I after every sixtieth work piece has been rection of its sliding movement.

11 ground, while an advance of fifteen ratchet teeth for each complete reciprocation of said piston will cause the dressing mechanism to operate after every four work pieces have been ground. Witha sixty-tooth ratchet wheel and the fourgroove edge cam H0, an advance of one ratchet tooth with each complete reciprocation of the piston 92 will cause the wheel dressing mechanism to operate after every fifteen work pieces have been ground, while an advance of fifteen ratchet teeth with each/reciprocation of said piston will cause the wheel dressing mechanism to operate after each work piece has been ground. The friction washers III clamped to the remote ends of the ratchet wheel I and cam wheel I00 serve to prevent said wheels from overrunning during the feed movement thereof, while the safety pawl I06 prevents said wheels from turning in a reverse direction during the return movement of the feed pawl MI.

The cam roller 35 may be adjusted by means of the screw 38 to properly locate the profile on the working face of the grinding wheel I. The length of th return or spring actuated stroke of the traversing slide II is regulated by means of the adjustable stop screw 54; and said traversing slide may be disposed parallel with or at an oblique angle to the rotary axis of the grinding wheel by adjusting the swivel mounted guide plate for said slide relative to the feed-up slide I0, the screw I9 serving to lock the swivel mounted plate in the desired position of angular adjustment on said feed-up slide. After each dressing operation, the diamond 25 is automatically fed in th direction ofthe grinding wheel axis to remove a certain amount of stock from the grinding wheel I. This automatic feed movement is imparted to the wheel dressing diamond 25 by the feed screw 43 for the feed-up slide I0, which feed screw is rotated a small amount by the feed-up pawl 46 after each dressing operation. As the traversing slide I I nears the end 01' its spring-actuated return stroke, the stop screw 54 carried by said slide engages the dog 56 fixed to the shaft 48, thereby rotating said shaft in a direction which will impart a feed movement to the pawl 46 pivoted on the arm 47 fixed to said shaft, The amount of feed movement imparted to the wheel dressing diamond 25 may be varied by adjusting the stop screw carried by the pawl supporting lever 41, adjustment of this screw changing the length of the return move.-

ment of said pawl 46 from feed position. When.

necessary, the diamond maybe advanced in the direction of the grinding wheel by manually rotating the feed screw 43 by means of the crank 49 thereon.

As stated above, when the wheel slide 4 is retracted to remove a finished work piece from the machine, the cam plate 61 opens the air valve 63, thereby raising the piston 92 in the cylinder 65 and imparting a rotary feed movement to the ratchet wheel I00 and cam wheel I08. This upward movement of the piston 92 permits flow of the air from the cylinder 55 to the air cylinder I24, thereby moving the piston I3I upwardly in the oil cylinder I30 and forcing oil into the hydraulic cylinder 26 fixed to the traversing slide II and thus causing said slide to move in one di- This upward movement of the piston I3I also causes the trip rod I 34 carried thereby to release the latch arm I9 for th cam plate 61, thus allowing the air valve 63 to close and removing the air pressure from the system and allowing the operating springs for the pistons 21 and I3I to return them to their original positions. Thus, the reversal oi travel of the traversing slide II is controlled by relieves the air pressure in the cylinder 65 and.

permits the piston 92 therein to be moved downwardly by its operating spring 93. When the slide 4 is moved forwardly to engage the grinding wheel with a new work piece, the cam plate 81 moves clear of the valve operating roller I8 for th air valve 63 and swings downwardly and is locked in this position by means of the latch arm I9.

The dressing cycle takes place while the operator is placing a new work piece in position. When the operator is ready to move the slide forward to present the grinding wheel to the work piece, the dressing is already completed, the time required for the dressing cycle being less than the time required to remove and replace the work piece. If, when the slide 4 is withdrawn and the counting mechanism is in position to cause the dresser to operate, the cam plate 61 will be released by the trip rod I34 at the end of the stroke of the piston I3! and the slide II, thus reversing the direction of travel of the slide. If the counting mechanism is not in position to allow the dresser to operate, depressing the air valve 63 by withdrawing the slide 4 merely operatesthe counting mechanism by raising the piston 92 and rotating the cam wheel I03 a predetermined amount, the piston staying at the top of its stroke until the slide is again moved forward and the air valve 63 is released by the cam plate 61 and the piston 92 drops to its normal position. This counting cycle is repeated with each back and forward movement of the slide 4 until the counting mechanism reaches the position shown in Fig. 15 with the roller II3 seated in the groove "19:: of the cam I 09 so as to release the valve H5 and allow it to raise and operate the dresser.

As stated above, the contour of the working face of the grinding wheel is determined by the contour of the cam edge of the cam plate fixed to the diamond slide. As shown diagrammatically in Fig. 24, the cam edge 34 of the cam plate 32 carried by the diamond slide I2 is longitudinally concave, whereby the dressing diamond moves both longitudinally and transversely relatlve to the grinding wheel axis to true and dress a grooved peripheral working face 3411 on said wheel corresponding to the shape of the cam edge of the cam plate. With this arrangement, the diamod 25 contacts the wheel face 34a during both forward and rpium strokes of the traversing slide II.

The-diagram shown in Fig. 25 illustrates an arrangement which is desirable for dressing a grinding wheel Ia having a straight or slightly curved conical or beveled working face. In this arrangement, a cam plate I46 is secured to the underside of the diamond slide I2 by means of the screw 33 and has a straight cam edge I41 disposed at an oblique angle to the direction of movement of the traversing slide i I; and a rocker I48 is journaled on the pivot bolt 36 fixed to the guide plate I5 for said traversing slide and has a V-shaped radial projection I49 that is located between the opposite ends of said rocker and makes substantial line contact with said cam edge of said cam plate. One arm I50 of the rocker I48 has a stop screw II thereon which abuts against the adjacent side face of the traversing slide II and limits the swinging movement of said rocker in one direction; and the other arm I52 of said rocker has a stop screw I53 thereon which is adapted to abut against said traversing slide and limit the swinging movement of said rocker in the opposite direction. The friction between the cam plate I46 and the V-shaped radial projection I49 on the rocker I 48 causes said rocker to rock from one position to the other when the traversing slide II is reciprocated. During the forward or fluid pressure actuated stroke of the traversing slide I I, the rocker I48 is rocked by the cam plate I46 in a direction that will swing the cam contacting end of the V-shaped projectlon I49 in the direction of the grinding wheel Ia and thus permit the diamond slide I2 to move far enough in such direction to bring the diamond 25 into contact with the wheel face I4Ia. During the return stroke of the traversing slide I2, the cam plate I46 rocks the rocker I48 in the reverse direction and thus increases the distance between the cam contacting end of the V-shaped projection I49 and the grinding wheel, thereby moving the diamond slide away from said grinding wheel and enabling the diamond to clear the wheel face during the entire return stroke of said traversing slide. By this arrangement, the conical wheel face MM is dressed by movement of the diamond thereacross from the sharp corner A of said face to the blunt corner thereof; and no dressing operation is performed during the return movement of said diamond, thereby preventing the diamond from breaking down the sharp corner of said wheel face or marking the same during such return movement.

Obviously, the hereinbefore described grinding wheel truing and dressing mechanism admits of considerable modification without departing from the invention. Therefore, I do not wish to be limited to the precise arrangements shown and described.

What I claim is:

1. In a grinding machine including a work support, a grinding wheel movable into engagement with and disengagement from a workpiece on said work support, and a truing element for said grinding wheel, the combination of a fluid pressure system for moving said truing element into engagement with said grinding wheel, said system comprising a, fluid pressure cylinder operatively connected to said truing element for moving the latter intoengagement with said grinding wheel, a second fluid pressure cylinder for supplying fluid pressure to said first mentioned cylinder, a master valve, a fluid pressure cylinder for operating said master valve and for supplying fluid pressure to said second cylinder, a control valve operable by each disengaging movement of said grinding wheel to admit fluid pressure to said master valve operating cylinder to operate the same, said master valve being interposed between said second and master valve operating cylinders, means for holding said master valve in closed position, and a connection between said master valve operating cylinder and said valve closing means and operable by a predeterminable number of operations of said master valve operating cylinder to release said master valve and permit the same to open.

2. In a grinding machine including a work support, a grinding wheel movable into engage- 14 ment with and disengagement from a workpiece on said support, a truing tool for said grinding wheel movable into andout of engagement therewith, the combination of a fluid pressure operated system for moving said truing tool into engagement with said grinding wheel after a predetermined number of disengaging movements of the latter from the work piece, said system comprising a fluid pressure cylinder. operatively connected to said truing element for moving the same into engagement with said grinding wheel, a second fluid pressure cylinder for supplying fluid pressure to said first mentioned cylinder to operate the same, a master valve, fluid pressure cylinder for operating said master valve and said second cylinder, a piston in said master valve operating cylinder, a control valve operable by each grinding wheel disengaging movement to admit fluid pressure to said master valve operating cylinder to operate the piston therein, said master valve being interposed between said second and master valve operating cylinders, a lever for holding said master --valve in closed position, a rotary edge cam cooperating with said lever and having a portion for holding said lever in valve closing position and a portion that will release said lever and permit said master valve to open, and an operative connection between said piston and said rotary edge cam, whereby said cam is rotated to lever releasing position by a predetermined number of operations of said piston.

3. The combination set forth in claim 2, in which the operative connection between said piston and said rotary edge cam comprises a ratchet wheel rotatable with said cam and a pawl cooperating with said ratchet wheel and operated by said piston.

4. The combination set forth in claim 2, in which the operative connection between said piston and said; edge cam comprises a ratchet wheel rotatable with said edge cam, a' lever piv- .otal about the rotary axis of said ratchet wheel,

a pawl pivotally supported on said last mentioned lever and engaging said ratchet wheel, a connection between said piston and said lever for rotating the latter and said pawl about the rotary axis of said ratchet wheel to rotate the same a predetermined distance each time said piston is operated, and means for varying the stroke of said piston to vary the amount of movement imparted to said ratchet wheel by each stroke of said piston.

5. The combination set forth in claim 2, in which the operative connection between said piston and said edge cam comprises a ratchet wheel rotatable with said edge cam, a lever pivotal about the rotary axis of said ratchet wheel, a pawl pivotally supported on said last mentioned lever and engaging said ratchet wheel, a-connection between said piston and said lever for rotating the latter and said pawl about the rotary axis of said ratchet wheel to rotate the same each timesaid piston is operated, andmeans for varying the stroke of said piston to ,vary the amount of rotary movement imparted to said ratchet wheel by each stroke of said piston.

6. The combination set forth in claim 2, in which a fluid pressure conduit communicates with said second cylinder through said master valve, a manually operable valve. is located in said conduit between said second cylinder and the source of fluid pressure supply for said conduit and is adapted to be opened at the will-of the operator to supply fluid PrQSSU Q W said sectioned cylinder to move said truing tool into engagement with said grinding wheel.

7. In a grinding machine including a work support, a rotary grinding wheel, a wheel slide for supporting said grinding wheel for engagement with and disengagement; from a work piece on said support, and a truing tool for said grinding wheel movable into and out of engagement therewith, the combination of a fluid pressure operated system for moving said truing tool into engagement with said grinding wheel after a predetermined number of disengaging movements of the latter from the work piece, said system comprising a fluid pressure cylinder operatively connected to said truing element for moving the same into engagement with said grinding wheel, a second fluid pressure cylinder for supplying fluid pressure to said first mentioned cylinder to operate the same, a master valve, a fluid pressure cylinder for operating said master valve and for supplying fluid pressure to said second cylinder to operate the latter, a self-closing control valve for admitting fluid pressure to said master valve operating cylinder, a cam carried by said wheel slide for opening said control valve during each grinding wheel disengagin movement of said wheel slide, said master valve being interposed between said second and master valve operating cylinders, an operative connection between said master valve operating cylinder and said master valve for causing said master valve to open after a predeterminable number of operations of said master valve operating cylinder, and a trip member operable by said second cylinder for rendering said cam inoperative to close said control valve.

8. In a grinding machine including a work support, a grinding wheel movable into engagement with and disengagement from a work piece on said support, and a truing tool for said grinding wheel movable into and out of engagement therewith, the combination of a fluid pressure operated system for moving said truing tool into engagement with said grinding wheel after a predetermined number of disengaging movements of the latter from the work piece, said system comprising a fluid pressure cylinder operatively convalve, a manually operable valve is located in said conduit between said third cylinder and a source of fluid pressure therefor for said conduit and is adapted to be opened at the will of the operator to supply fluid pressure to said third cylinder and thereby operate said common piston and said first mentioned cylinder to move said truing tool into engagement with said grinding wheel.

10. In a grinding machine including a support for a work piece, a rotary grinding wheel, and a wheel slide for supporting said grinding wheel for movement into and out of engagement with said work piece, and a truing tool for said grinding wheel movable into and out of engagement therewith, the combination of a fluid pressure cylinder operatively connected to said truing element for moving the same into engagement with said grinding wheel, a second fluid pressure cylinder for supplying fluid pressure to said first mentioned cylinder to operate the same, a third cylinder co-axial with said second cylinder, a piston common to said second and third cylinders, a fourth fluid pressure cylinder for supplying fluid pressure to said third cylinder to actuate the common piston of said second and third cylinders, a piston in said fourth cylinder, a self-closing control valve operable by each grinding wheel disengaging movement of said wheel slide to admit fluid pressure to said fourth cylinder to actuate the piston therein, a self-opening master valve interposed between said third and fourth cylinders, means releasable by a predetermined number of operations of the piston in said fourth cylinder for holding said master valve in closed position, a cam carried by said wheel slide and adapted to open said control valve when said nected to said truing element for moving the same into engagement with said grinding wheel, a second fluid pressure cylinder for supplying fluid pressure to said first mentioned cylinder to operate the same,a third cylinder co-axial with said second cylinder, a piston common to said second and third cylinders, a fourth fluid pressure cylinder for supplying pressure to said third cylinder to actuate thecommon piston of said'second and third cylinders, a piston in said fourth cylinder, a control valve operable by each grinding wheel disengaging movement to admit fluid pressure 1 to said fourth cylinder to actuate the piston therein, a master valve interposed between said third and fourth ,cylinders,'a lever for holding said master valve in closed position, a rotary cam cooperating with said lever for. holding the latter in valve closing position and in a position permitting said master valve to open, and an operative connection between said cam and the piston in said fourth cylinder, whereby said cam is rotated to lever releasing position by a predetermined number of operations of the piston in said fourth cylinder.

9. The combination set forth in claim 8, in which a fluid pressure conduit communicates with said third cylinder through said master wheel slide is moved into grinding wheel disengaging position, means for releasably holding said cam in position to open said control valve in said last mentioned position of said wheel slide, and means carried by said common piston for rendering said cam holding means inoperative during the operative stroke of said common piston to thereby permit said control valve to close.

11. The combination set forth in claim 10, in which a pair of parallel links connect said cam to said wheel slide for movement relative thereto and to said control valve, and said cam is held in valve opening position by a latch lever which is pivoted to said wheel slide and is adapted to be released by the means carried by said common piston.

12. The combination set forth in claim 10, in which the means for releasably holding the cam in position to open said control valve is carried by the wheel slide and means is provided for adjusting said means and said cam longitudinally of said wheel slide.

13. The combination set forth in claim 10, in which a pair of parallel links connects said cam to said wheel slide for movement relative thereto and to said control valve, said cam is held in valve opening position by a latch lever which is pivoted to said wheel slide and is adapted to be released by the means carried by said common piston and means is provided for adjusting said cam, links and latch lever longitudinally of said wheel slide.

14. The combination set forth in claim 10, in which a support is secured to said wheel slide for adjustment longitudinally thereof, a pair of links connects said cam to said support for movement relative thereto and to said control valve and said cam is held in valve opening position by 17 a latch lever which is pivoted to said support and is adapted to be released by the means carried by the common piston.

15. In a grinding machine including a support for a work piece, a rotary grinding wheel, and a wheel slide for supporting said grinding wheel for movement into and out of engagement with said work piece, and a truing tool for said grinding wheel movable into and out of engagement therewith, the combination of a fluid pressure system including a fluid pressure cylinder operatively connected to said truing element for moving the same into engagement with said grinding wheel, a reservoir containing an operating fluid and a second fluid pressure cylinder for supplying such fluid to said first mentioned cylinder to operate the same, a second fluid pressure system including a third cylinder for operating said second cylinder, a fourth fluid pressure cylinder for supplying fluid pressure to said third cylinder to operate the same, a fluid pressure supply conduit opening into said fourth cylinder, a control valve in said conduit and operable by each grinding wheel disengaging movement to admit fluid pressure through said conduit to said fourth cylinder to operate the same, a self opening master valve for controlling the flow of fluid pressure between said third and fourth cylinders, means for holding said master valve in closed position, and means operated by a predetermined number of operations of said fourth cylinder for releasing said valve closing means to permit said master valve to open.

16. In a grinding machine including a support I for a work piece, a rotary grinding wheel, and a wheel slide for supporting said grinding wheel for movement into and out of engagement with said work piece, the combination of a truing mechanism for the working face of said grinding wheel comprising a traversing slide movable longitudinally of the grinding wheel axis, a truing tool slide supported on said traversing slide for movement therewith and for reciprocating movement relative thereto transverse to said grinding wheel axis, a truing tool fixed to said tool slide for movement therewith into and out of engagement with said grinding wheel, and means movable with said tool slide cooperating with means fixed to said machine for reciprocating said tool slide on said transverse slide during the reciprocating movement of the latter, said tool slide reciprocating means comprising a cam plate fixed to said tool slide and having a cam edge that extends in the direction of movement of said traversing slide and follows the contour desired for the working face of said grinding wheel, and a rocker lever journaled on said machine and having a portion cooperating with said cam edge and positioned thereby during movement of said traversing slide in one direction to permit said truing tool to engage said working face and positioned by said cam edge during movement of said traversing slide in the opposite direction to move said tool clear of said working face.

1'7. In a grinding machine including a support for a work piece, a rotary grinding wheel, and a wheel slide for supporting said grinding wheel for movement into and out of engagement with said work piece, the combination of a truing mechanism for the working face of said grinding wheel comprising a traversing slide movable longitudinally of the grinding wheel axis, a truing tool slide supported on said traversing slide for movement therewith and for reciprocating movement 18 relative thereto transverse to said grinding wheel axis, a truing tool fixed to said tool slide for movement therewith into and out of engagement with said grinding wheel, and means movable with said tool slide cooperating with means fixed to said machine for reciprocating said tool slide on said transverse slide during the reciprocating movement of the latter, said grinding wheel having a beveled peripheral working face, said tool slide reciprocating means comprising a cam plate fixed to said tool slide and having a straight cam edge disposed at an oblique angle to the direction of movement of said traversing slide, and a rocker lever journaled on said machine and having a portion cooperating with said cam edge and positioned thereby during the movement of said traversing slide in one direction to cause the truing tool to move along said beveled working face from the sharp corner thereof to the blunt corner thereof and positioned by said cam edge during the movement of said traversing slide in the opposite direction to cause said tool to move clear of said working face.

18. Ina grinding machine including a support for a 'work piece, a rotary grinding wheel, and a wheel slide for supporting said grinding wheel for movement into and out of engagement with said work piece, the combination of a truing mechanism for the, working face of said grinding wheel comprising a traversing slide movable longitudinally of the grinding wheel axis, a truing tool slide supported on said traversing slide for movement therewith and for reciprocating movement relative thereto transverse to said grinding wheel axis, a truing tool fixed to said tool slide for movement therewith into and out of engagement with said grinding wheel, means movable with said tool slide cooperating with means fixed to said machine for reciprocating said tool slide on said traversing slide during the reciprocating movement of the latter to move said truing tool across the working face of said grinding wheel during the movement of said traversing slide in one direction and to move said truing tool clear of said working face during the return movement of said traversing slide, and means for feeding said traversing slide a predeterminable distance in the direction of said grinding wheel with each complete reciprocation of said traversing slide, said last mentioned means comprising a feed-up slide movably supporting said traversing slide and mounted on said machine for sliding movement transversely of said wheel axis, a feed screw journaled for rotary but non-axial sliding movement on said feed-up slide and threadedly engaging a stationary part of said machine, a ratchet wheel secured to said feed screw, a pawl coopcrating with said ratchet wheel, and means operated by the movement of said traversing slide in one direction for actuating said pawl to rotate said ratchet wheel in feeding direction.

19. In a grinding machine including a support for a work piece, a rotary grinding wheel, and a wheel slide for supporting said grinding wheel for movement into and out of engagement with said work piece, the combination of a truing mechanism for the working face of said grinding wheel comprising a traversing slide movable longitudinally of the grinding wheel axis, a truingvtool slide supported on said traversing slide for movement therewith and forreciprocating movement relative thereto transverse to said grinding wheel axis, a truing tool fixed to said tool slide for movement therewith into and out of engagement with said grinding wheel, means movable with said tool slide cooperating with means fixed to said machine for reciprocating said tool slide on said traversing slide during the reciprocating movement of the latter to move said truing tool across the working face of said grinding wheel during the movement of said traversing slide in one direction and to move said truing tool clear of said working face during the return movement of said traversing slide, and means for feeding said traversing slide a predeterminable distance in the direction of said grinding wheel with each complete reciprocation of said traversing slide, said last mentioned means comprising a feed-up slide movabl supporting said traversing slide and mounted on said machine for sliding movement transversely of said wheel axis, a feed screw journaled for rotary but non-axial sliding movement on said feed-up slide and threadedly engaging a stationary part of said machine, a ratchet wheel secured to said feed screw, a lever pivoted on said feed-up slide for movement transversely of the said ratchet wheel, a pawl mounted on said lever and cooperating with said ratchet wheel, means operated by the movement of said traversing slide in one direction for actuating said lever to impart a feed movement to the pawl thereon, and means for imparting a return movement to said lever and pawl during the movement of said traversing slide in the other direction.

20. In a grinding machine including a support for a work piece, a rotary grinding wheel, and a wheel slide for supporting said grinding wheel for movement into and out of engagement with.

said work piece, the combination of a truing mechanism for the working face of said grinding wheel comprising a traversing slide movable longitudinally of-the grinding wheel axis, a truing tool slide supported on said traversing slide for movement therewith and for reciprocating movement relative thereto transverse to said grinding wheel axis, a truing tool fixed to said tool slide for movement therewith into and out of engagement with said grinding wheel, means movable with said tool slide cooperating with means fixed to said machine for reciprocating said tool slide on said traversing slide during the reciprocating movement of the latter to move said truing tool across the working face of said grinding wheel during the movement of said traversing slide in one direction and to move said truing 'tool clear of said working face during the return movement of said traversing slide, a fluid cylinder fixed to said traversing slide, a piston mounted in said cylinder in abutting relation to a stationary part of said machine, whereby said traversing slide is moved in one direction of its sliding movement when fluid pressure is supplied to said cylinder, a spring for moving said traversing slide in the opposite direction of its sliding movement, and means for admitting fluid pressure to said cylinder after a predetermined number of grinding wheel disengaging movements of said wheel slide.

21. In a grinding machine including a support for a work piece, a rotary grinding wheel, and a wheel slide for supporting said grinding wheel for movement into and out of engagement with said work piece, the combination of a -truing mechanism for the working face of said grinding wheel comprising a traversing slide movable longitudinally of the grinding wheel axis, a truing tool slide supported on said traversing slide for movement therewith and for reciprocating movement relative thereto transverse to said grindi wheel axis, a truing tool fixed to said tool slide for movement therewith into and out ofenga'gement with said grinding wheel, means movable with said tool slide cooperating with means fixed to said machine for reciprocating said tool slide on said traversing slide during the reciprocating movement of the latter to move said truing tool across the working face of said grinding wheel during the movement of said traversing slide in one direction and to move said truin'g tool clear of said working face during the return movement of said traversing slide, a fluid pressure cylinder operativel connected to said traversing slide to operate the same, and means for admitting fluid pressure to said cylinder after a predeterminable number of grinding wheel disengaging movements of said wheel slide.

22. In a grinding machine including a support for a work piece, a rotary grinding wheel, and a wheel slide for supporting said grinding wheel for movement into and out of engagement with said work piece, the combination of a truing mechanism for the working face of said grinding wheel comprising a traversing slide movable longitudinally of the grinding wheel axis, a truing tool slide supported on said traversing slide for movement therewith and for reciprocating movement relative thereto transverse to said grinding wheel axis, a truing tool fixed to said tool slide for movement therewith into and out of engagement with said grinding wheel, means movable with said tool slide cooperating with means fixed to said machine for reciprocating said tool slide on said travers ng slide durin the reciprocating movement of the latter to move said truing tool across the working face of said grinding wheel during the movement of said traversing slide in one direction and to move said truing tool clear of said working face during the return movement of said traversing slide, and a fluid pressure system for operating said traversing slide, said system including a fluid pressure cylinder operatively connected to said traversing slide, a second fluid pressure cylinder for supplying fluid under pressure to said first mentioned cylinder, a normally closed master valve, a fluid pressure cylinder for opening said master valve and for supplying fluid pressure to said second cylinder, a control valve operable by each grinding wheel disengaging movement of said wheel slide to admit fluid pressure to said valve opening cylinder to operate the same, said normally closed master valve being interposed between said second and valve opening cylinders. and an operative connection between said valve opening cylinder and said master valve adapted to cause said master valve to open after a predeterminable number of operations of said valve opening cylinder.

JOHN W. RUNDT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,416,462 Hanson May 16, 1922 1,684,485 Guild et al. Sept. 18, 1928 1,825,753 Nenninger Oct. 6, 1931 2,171,902 Wood Sept. 5, 1939 2,178,875 Kearns Nov. 7, 1939* 2,335,207 Flygare'et al. Nov. 23, 1943 2,409,240 Barker et al, Oct. 15, 1946 

